1. Field of the Invention
The invention is related to the field of communications and, in particular, to delivery of messages.
2. Statement of the Problem
In many mobile networks, text and multimedia messaging has become a very popular mode of communication. One example of a text messaging service is Short Message Service (SMS), which is a communication protocol allowing the exchange of short text messages (i.e., 160 characters) between mobile devices. One example of a multimedia messaging service is Multimedia Message Service (MMS), which is a communication protocol allowing the exchange of multimedia messages (i.e., digital pictures, media clips, etc) between mobile devices. Often times, mobile users more frequently use text or multimedia messaging for communication than voice calls.
Text messages are transmitted over signaling channels of a mobile network, such as over SS7 channels. An SMS Center (SMSC) in the mobile network has a store-and-forward system for delivering text messages to their destinations. Upon initially receiving a text message, the store-and-forward system first stores (persistently) the text message, and then initiates a delivery attempt for the text message. If the first delivery attempt is unsuccessful, then the store-and-forward system enters a retry process. For the retry process, the network operator predefines a global retry configuration for all text messages. Thus, the store-and-forward system identifies the global retry configuration, and then attempts to deliver the text message to the destination according to the global retry configuration. For example, the global retry configuration may define that a maximum of three retry attempts should be made at an interval of thirty minutes. After the failed delivery of the text message, the store-and-forward system waits for thirty minutes and then initiates a retry attempt for the text message. If the first retry attempt is unsuccessful, then the store-and-forward system again waits for thirty minutes and initiates a second retry attempt. This process of retrying delivery occurs three times before the text message is discarded. A similar process occurs for multimedia messages (e.g., MMS) or other types of messages.
One problem encountered by network operators is that when the mobile network becomes congested, there may be a higher incident of failed deliveries for SMS messages. For example, where there is a large event, such as a New Years Eve celebration, a large amount of SMS traffic can overload a Mobile Switching Center (MSC), an SMSC, or other network elements. If an MSC shuts down due to the high traffic volume, many SMS messages may be lost.
To solve this problem, network operators may deploy more SMSCs or MSCs in a congested area to handle traffic congestion problems. However, this is an expensive solution to the congestion problem, especially considering that the traffic congestion could be temporary. Network operators may also control SMS message traffic by limiting the number of SMS messages that are sent by the SMSC. The presently-used methods control all SMS traffic delivered from the SMSC. For example, if message congestion is identified in one MSC, then the SMSC limits the number of SMS messages it delivers to the congested MSC and other MSCs in the mobile network. An SMSC may serve areas that have high SMS traffic congestion as well as areas that have no SMS traffic congestion. Unfortunately, the SMSC limits the number of SMS messages delivered to the areas that have no SMS traffic congestion, even when there is no need to do so.